Shear Strength of Organic Clay in Kolkata Region

Organic clay is invariably found in the upper reaches of the soil layers in Kolkata region. To understand the strength characteristics of organic clay and also the various factors affecting its strength characteristics, consolidated undrained triaxial tests were conducted on organic clay with organic content 0, 7, 15, 20 and 26 % consolidated at effective consolidation stress (p'(0)) 50, 100, 150 and 200 kPa. From the test results it was found that the normalized undrained cohesion for different consolidation pressure increases bi-linearly with increase in organic content. Further, the angle of internal friction phi' was found to be dependent on the effective confining pressure for organic clay with organic content greater than 15 %. Organic clay with higher organic content showed higher values of effective angle of internal friction.